Method for decontaminating a permeable subterranean formation

Abstract

The present invention is a process to oxidize a contaminant in a permeable subterranean formation by introducing an aqueous treating solution into the formation which solution contains hydrogen peroxide and a compound to control the mobility of the aqueous solution by increasing the viscosity, the density, or modifying the interfacial properties of the aqueous solution within the formation. The aqueous treating solution may also contain stabilizers for the hydrogen peroxide, free radical initiators, or free radical traps. Optionally, the formation may be pretreated to modify the permeability of the formation, to deactivate or remove hydrogen peroxide decomposition catalyst or to uniformly distribute free radical initiators therein.

What is claimed is: 
     
       1. A process for chemically oxidizing a contaminant in a permeable subterranean formation containing groundwater comprising introducing an aqueous treating solution into the formation said aqueous treating solution comprising 0.1% to 20% hydrogen peroxide and from 1 to 100 kilograms of a hydratable polymeric material per cubic meter of aqueous treating solution to provide sufficient viscosity to modify the distribution of the aqueous treating solution within the subterranean formation to provide sufficient hydrogen peroxide proximate to the contaminant to oxidize the contaminant to a less objectionable form yet minimize the distribution of hydrogen peroxide to portions of the subterranean formation free from the contaminant. 
     
     
       2. The process of claim 1 further including incorporating 0.5 to 40 kilograms per cubic meter of a surfactant into the aqueous treating solution thereby modifying the interfacial properties of the aqueous treating solution. 
     
     
       3. The process of claim 1 further including incorporating 0.5 to 40 kilograms per cubic meter of a phosphate salt into the aqueous treating solution thereby modifying the interfacial properties of the aqueous treating solution. 
     
     
       4. The process of claim 1 further including incorporating 0.5 to 40 kilograms per cubic meter of a densifier into the aqueous treating solution. 
     
     
       5. The process of claim 1 further including incorporating 0.5 to 40 kilograms per cubic meter of a phosphate salt as a densifier into the aqueous treating solution. 
     
     
       6. The process of claim 1 wherein an aqueous pretreatment fluid is introduced into the subterranean formation prior to the introduction of the aqueous treating solution, said pretreatment fluid comprising a compound selected from the group consisting of a hydrogen peroxide decomposition catalyst, a chelating agent, a free radical activator, and a phosphate salt. 
     
     
       7. The process of claim 6 wherein the aqueous pretreatment fluid comprises a phosphate salt. 
     
     
       8. The process of claim 6 wherein the aqueous pretreatment fluid comprises a free radical activator. 
     
     
       9. The process of claim 6 wherein the aqueous pretreatment fluid comprises a chelating agent. 
     
     
       10. The process of claim 6 wherein the aqueous pretreatment fluid comprises a potassium salt of phosphoric acid. 
     
     
       11. The process of claim 6 wherein the aqueous pretreatment fluid also comprises hydrogen peroxide. 
     
     
       12. The process of claim 6 wherein the aqueous pretreatment fluid comprises a hydrogen peroxide decomposition catalyst. 
     
     
       13. The process of claim 6 wherein the aqueous pretreatment fluid also comprises a free radical inhibitor. 
     
     
       14. The process of claim 13 wherein the free radical inhibitor is a compound selected from the group consisting of allyl alcohol, catechol, 1,10-orthophenanthroline, butene-1, 4-diol, phenol, resorcinol, and hydroquinone. 
     
     
       15. The process of claim 6 wherein the aqueous pretreatment fluid comprises a free radical activator and a free radical inhibitor. 
     
     
       16. The process of claim 15 wherein the free radical activator is a compound selected from the group consisting of an iron salt, a copper salt or a complex salt of iron or copper. 
     
     
       17. The process of claim 15 wherein the free radical inhibitor is a compound selected from the group consisting of allyl alcohol, catechol, 1,10-orthophenanthroline, butene-1, 4-diol, phenol, resorcinol, and hydroquinone. 
     
     
       18. The process of claim 1 wherein the hydratable polymeric material is a compound selected from the group consisting of hydratable polysaccharides, polyacrylamides, and polyacrylamide copolymers.